Direct Measurements of the Mass of Municipal Biowaste Separated and Recycled at Source and Its Role in Circular Economy—A Case Study from Poland

Determining the amount of biowaste generated, separated, and recycled at source in households (BHrecycled) is crucial for assessing its potential inclusion in the total mass of waste prepared for reuse and recycling on the country level. Although the EU has introduced standardized rules for BHrecycled measurement, it is still a major challenge. This study, the first to be conducted on a large scale in Poland and the EU countries, aimed to determine the actual mass of BHrecycled (kitchen waste (B K ) per capita per year (kg/(capita·year)) and garden waste (B G ) per square meter of green area (kg/(m 2 ·year)) in 1150 households that use an active composting unit located in more than 400 municipalities in all the voivodeships in Poland. Each municipality is characterized by individual MSW generation (MSW G ) values (the amount of waste generated per capita per year). The MSW G values of the municipality where the household was located were used to group the data of B K and B G . In Poland, the average masses of B K and B G remained within the ranges of 81.02–107.49 kg/(capita·year) and 1.02–2.87 kg/(m 2 ·year), respectively, across the MSW G value. However, there was no clear statistical relationship between the MSW G value and B K or B G . The average masses of B K and B G were ca. 97 kg/(capita·year) and ca. 2 kg/(m 2 ·year). These results enable the determination of the total amount of BHrecycled in Poland. By incorporating these findings into waste management, strategies, monitoring, and reporting practices can be improved. Moreover, it promotes compliance with the EU recycling targets.